This is another megaloblastic bone marrow specimen. Both the erythrocytic and the granulocytic series are involved. The cells are deficient in chromatin and are larger than normal cells. The larger granulocytes indicated by the arrows are macro- or giant metamyelocytes and bands. The nuclei stain light and are quite different from normal metamyelocytes and bands. Even the segmented cells may have extremely light-staining lobes. These changes in the granulocytes appear before changes in the NRBCs and disappear after the NRBCs become normal. If the granulocytes are not involved, then B12 or folate deficiency is not the cause for the megaloblastosis.
Course Section: 05. Nucleated Red Blood Cells
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